Subject: AW: [IBIS-Users] Buffer ramp rates & loading question.
From: Lenski Eckhard (eckhard.lenski@siemens.com)
Date: Thu Feb 13 2003 - 23:30:25 PST
Hello John,
some quick answers
1) The powerclamp-curve should start at vcc with a value of 0mA; depending on your extraction method and the possibility that you might have an internal pullup/pulldown (which will be added to the clamp-behavior) this could be the reason, that at vcc the currentvalue isn't 0, but starts with e.g. 15uA or so.
2) as far as I know, there will be no problem for the simulator, but why don't you support waveforms for both r-fixture resistances ?( 4 waveforms with 50 ohm load and 4 waveforms with 300 ohm load )
3) the loading for the ramp values are defined by the value of rload, which you have to support ( it is up to you to define the value, but the default value is 50 ohm ). Furthermore ibis uses the termination scheme with rload to gnd for the rising ramp and rload to vcc for the falling ramp.
Regards
Eckhard
Eckhard Lenski
Siemens AG
ICN M&L OP Bsl TDC TC3
Phone : 0049 89 722 27776
Fax : 0049 89 722 44692
Email : eckhard.lenski@siemens.com
-----Ursprüngliche Nachricht-----
Von: John Phillippe [mailto:john.phillippe@motorola.com]
Gesendet: Freitag, 14. Februar 2003 00:20
An: ibis-users@eda.org
Betreff: [IBIS-Users] Buffer ramp rates & loading question.
Hello People,
I have a few quick questions below:
1. I have gotten a few warnings about the power clamp values that never
become zero. How can I fix the warnings?
WARNING - Model Pad_fc_drive10: POWER Clamp : Minimum value never
becomes zero
2. I have some slow I/O drivers that take a long time to settle for the
rising and falling curves. To help the curves settle faster, I want
to use 300 Ohms for the load. Normally I would use 50 Ohms load for the
I/O drivers. I am wondering if I can use 300 Ohms load for the slow
drivers? Is it going to be a simulator problem if some of the buffers
use 50 Ohm loads, and others 300 Ohms loads?
3. The keyword [Ramp] gives you the ramp rate on how long it takes the
output to switch from one state to another. It is define by 20% to 80%
voltage swing of the output to the time it takes to swing the voltage.
What is the pin loading used for this measurement?
-- John Phillippe SPS, 32 Bit Embedded Controller Division, IC Creation Motorola - 512-895-1835 Austin, TX - john.phillippe@motorola.com|------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993 |------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993
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